Can’t tell you how many times I’ve saved myself time/money/frustration by being an inveterate archiver of email [including sent email]. Invariably, something I sent to someone will be needed down the line by someone else, and if I can dig it up … I save everyone heaping amounts of time.
I buy into INBOX Zero, but I do project-based folders. I do a lot of proposal management, so each separate proposal gets its own Outlook folder in a .PST dedicated to just proposals for 2008. [Twenty-one to date this year, and that’s not counting multiple revisions on at least five of those proposals.] That’s really it, though. If a proposal or project is active and generating email, I put it in as a Favorite Folder in Outlook, which puts it in the left-hand menu for rapid drag/drop action. Rarely I put stuff in an @Actions folder; I’m better off leaving it in my INBOX to stress myself into handling it, or sticking it in my task manager and filing the email if there are large attachments. I have to have it on the radar.
All proposals and projects are listed in the Favorites Folder, sorted by most urgent calendar-wise, due-first at the top. A typical listing is something like “2008-299 XYZ Widgets (9/26)” — the log number assigned internally [which is what Pricing, Procurement, and the Business Office pay the most attention to], then the title of the Proposal, then the due date in parentheses. If a colleague is heading the task but I’m still needing to stay current, I put their name in brackets, e.g. “2008-333 Acme PDQ Whatsits (9/5) [Jaime]”. When a proposal goes out, I pull the folder out of the Favorites list, because it’s off my radar. If we get to do a rev on the propsal, back it comes.
Sent mail gets auto-archived to its own sentmail PST after two weeks. The archive is a smidge slower to open, and I’m more likely to need something in Sent Items that’s recent; I have to hunt more for older stuff, but when I’m hunting, I typically need to be hunting, and that’s okay.
Also, I back up … religiously. I’ve been burned.
Because some might ask, I adhere to a classic Actions/Archives/Responses I0 setup at home. The only variants I have: I break up the archives and sentmail by year, just to keep the IMAP mailbox size down and cut search times. Archiving last year’s email is a very fun New Year’s Day task for me. [No, really, it is.]